Heavy metal diffusion under high hydraulic gradients and diffusion anisotropy through soft Bangkok clay | |
| Author | Almani, Zaheer Ahmed |
| Call Number | AIT Thesis no.GE-05-10 |
| Subject(s) | Clay--Thailand--Bangkok--Testing Heavy metals |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. GE-05-10 |
| Abstract | This study was broadly focused on two main targets. Firstly, it was concentrated towards the determination of contaminant transport parameters of the heavy metal Zinc moving through saturated Soft Bangkok Clay under high hydraulic gradients (250 and 500) in vertical and horizontal direction. Also, comparison of contaminant transport parameters determined under these conditions to the parameters determined under concentration gradient alone (pure diffusion) condition and its implications. Secondly, it was directed towards the determination of anisotropy in contaminant transport parameters and its implications the on environment. This anisotropy is due to presence of micro stratification, loose bond between adjacent layers, layers of more permeable and plate like flat particle orientation in natural sedimentary marine clay in horizontal bedding direction. Due to this heterogeneous nature of clay in horizontal direction, it has already been established that Soft Bangkok Clay is highly anisotropic in hydraulic conductivity. In total thirty two column tests were conducted and a theoretical model was applied to determine the relevant coefficients. Influent concentrations of 0.001 molar for ZnCI2 was applied for all tests. ZnC12 was dissolved in de-ionized distilled water to produce the metal solution at pH 4-5. Fifteen tests were conducted in vertical direction and seventeen were conducted in horizontal direction. Two larger cells pure diffusion tests were also conducted to study effect of size on parameters, one in vertical direction and other in horizontal direction. Two different source concentration conditions, constant and decreasing, were applied. Testing periods were ranged from 15 days to 60 days while hydraulic gradients were ranged from 0 to 500. The curves between relative concentration vs. time and pore volume were developed for the constant source condition and curves between source reservoirs concentrations vs. time were developed for decreasing source condition. At the end of each test, the soil columns were horizontally sectioned to extract the pore water and to determine the amount of free or in solution Zinc and Chloride in pore water with depth. DDW was used to dilute the Zinc present in pore water and the chemical analyses were performed with a spectrophotometer. The effective diffusion, De, and distribution, Kd, coefficients were determined by curve fitting using the computer code POLLUTE v 6.3. The distribution coefficients were cross checked by developing adsorption isotherms. The tortuosity and retardation factor were calculated by using the net average values of diffusion and distribution coefficients. |
| Year | 2005 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. GE-05-10 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Geotechnical Engineering (GE) |
| Chairperson(s) | Glawe, Ulrich; |
| Examination Committee(s) | Park, Kyung-Ho; Pham Huy Giao |
| Scholarship Donor(s) | Higher Education Commission Pakistan;Asian Institute of Technology Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2005 |